Method of making a metal petroleum sulfonate



Unite 1 rates METHOD OF MAKING A METAL PETROLEUM SULFON AT E No Drawing. Application January 16, 1956 Serial No. 559,129

5 Claims. (Cl. 252-33) This invention relates to the method of making a metal petroleum sulfonate and to a lubricant embodying such metal petroleum sulfonate as an additive.

Various methods have been proposed for the preparation of metal petroleum sulfonates. Many of these processes are quite complex involving a large number of treating steps. Also, when the petroleum stock used is quite heavy, e. g., a brightstock having a viscosity of greater than 80 Saybolt Universal seconds at 210 F., difliculties are encountered in that emulsification occurs upon treatment of the petroleum with acid without the formation of two separate phases. This complicates the problem of removing the impurities which would otherwise be removed merely by separation of the acid phase separating from the oil phase upon acid treatment.

In accordance with the present invention, an improved process is provided for making metal petroleum sulfonates from heavy oil stocks. This method involves treatment of the oil stock with oleum followed by extraction with an aqueous alcohol solution containing 60 to 100 weight percent alcohol. The extract is neutralized with a metal hydroxide to produce the metal petroleum sulfonate. By this simple process, a superbase additive is obtained, i. e., one having a high metal and ash content with resulting high activity and detergency. It is a feature of the invention that an isopropyl alcoholwater azeotrope containing 12.1 percent water can be used in this process, thus simplifying the solvent recovery steps.

An an optional and quite. advantageous feature of the invention, the alcohol extraction can be preceded by a treatment with weak alcohol solution, i. e., water containing 5 to 40 percent alcohol. This is advantageous in that the bulk of the sulfuric acid is removed in this preliminary alcohol treatment, thus substantially reducing the amount of metal sulfates to be handled in subsequent steps, and making it easy to obtain a highly purified product.

In this manner, a high quality lubricant additive is obtained with full benefit of all the processing advantages previously noted. When this material is mixed with lubricating oil of, say SAE5W to SAE-50 grade in an amount of 0.1 to 20 percent by weight based on the oil, a high detergency oil is obtained with improved characteristics. The additive of the invention is also useful in the formation of greases upon addition of suitable thickening agents.

According to more specific aspects of the invention, the starting material is a lubricating oil stock, such as a brightstock, having a viscosity of 80 to 700 Saybolt Universal seconds at 210 F. The advantages of the invention, however, are more apparent where the brightstock has a viscosity Within the more restricted range of 150 to 600 Saybolt Universal seconds at 210 F., and especially good results have been obtained with a brightstock having a viscosity within the range of 200 to 230 Saybolt Universal seconds at 210 F. This oil should have a viscosity index of at least 85, say 85 to 98.

atent In the sulfonation step, the oil starting material is contacted with a sulfonation agent of which fuming sulfuric acid and chlorosulfonic acid are especially suitable. A temperature within the range of 50 to 200 F., say F., is maintained during the sulfonation together with an .acid-to-oil weight ratio of 0.4:1 using 20 percent oleum. This ratio, however, can vary from 0.175 :1 to 0.7:1 Without departing from the invention, and the temperature and the time of sulfonation are in general not critical.

Where the preliminary extraction with a weak alcohol solution is utilized, the strength of the alcohol solution, which is important, varies between 5 and 40 percent. The alcohol employed can be isopropyl alcohol, although other alcohols can be utilized. Thus butyl alcohol, n-propyl alcohol, and other alcohols having up to 7 carbon atoms are suitable. Although the treating conditions are not critical, a typical treatment involves 10 percent isopropyl alcohol solution in an amount of /2 to 5 volumes per volume of sulfonated oil with a treatment time of 15 to 60 minutes, a temperature of 80 to F., and a pressure sufiicient to maintain a liquid phase.

When this preliminary treatment is utilized, the amount of sulfuric acid to be handled is greatly reduced since the sulfuric acid is largely removed in this first extraction step. In commercial operation, this extraction is carried out continuously in a column, the extract containing the residual sulfuric acid from the sulfonation step while the raffinate contains the sulfonated oil substantially free from sulfuric acid, i. e., as little as 1 to 2 percent.

Next, the rafiinate (or the sulfonation product if the previous treatment step is omitted) is extracted with more concentrated aqueous alcohol, i. e., containing 60 to 100 percent alcohol. This efficiently extracts the petroleum sulfonic acids in a highly purified form. In commercial operation, this step takes place in a column in a continuous fashion, the raffinate phase being essentially unreacted oil while the extract contains essentially all the sulfuric and sulfonic acids.

Although the treatment conditions are not critical, it can be mentioned that the alcohols suitable are those previously indicated for the first extraction step, a suitable treatment time is 15 to 60 minutes at room temperature with sufficient pressure to maintain a liquid phase.

If the preliminary treatment with relatively weak alcohol solution is utilized, the amount of strong alcohol varies from 1 to 5 volumes per volume of material treated, specifically, three volumes. Higher amounts than five volumes per volume of material treated are sometimes required if the preliminary treatment with weak alcohol is not carried out.

It is of special advantage to utilize the water alcohol azeotrope in this last-described treating step, i. e., 12.1 percent Water and 87.9 percent alcohol, as solvent recovery is greatly simplified when this azeotropic composition is employed.

When this step is completed, the extract is neutralized with metal salt of hydroxide solution or slurry under conditions insuring a complete neutralization of the sulfonic acid. Care should be taken not to heat the sulfonic acid portion above about F. during neutralization, as a black, viscous material may form if this temperature is exceeded. This normally involves a treatment time of 30 minutes to five hours, .and completeness of neutralization can be determined by a litmus paper test in the vapors at a temperature of 500 F. Preferably and advantageously, a calcium hydroxide-water slurry or other calcium compound is utilized to etfect neutralization. However, the alkaline earth metals are suitable in general for this purpose and give highly effective metal petroleum sulfonate products. Thus, a slurry of barium,

3 magnesium, tin or zinc hydroxide can be used advantageously. Moreover, with .some sacrifice of detergent and lubricating qualities in the finished oils, other metal compounds can be used such as hydroxide of lithium, potassium,.nickel, cobalt, cadmium, silver, iron, aluminum, copper, lead, barium; mercury and sodium.

The neutralized material is filtered to provide the petroleum metal sulfonatematerial which is suitable for use as an oil additive. If desired, one to three volumes of SAE-lO lubricating oil, Stoddard solvent, or pentane can be added before or' after the neutralization step to facilitate this filtration.- The diluent can be removed from the filtrate to obtain the final additive or, more preferably, where the diluent is SAE- or other light lubricating. oil, it can be: left in to facilitate dissolving of the additive in the lube oil stock.

Where there is no' preliminary treatment with weak alcohol, and' calcium hydroxide is utilized as the neutralizing agent, the product has two to three times the calcium content of calcium petroleum sulfonates prepared in the usual way and superior detergent action is obtained.

The sulfuric acid is readily removed where the weak alcohol treatment is utilized, so that sulfates do not have to be handled in subsequent steps of the process. Finally it will be noted that the number of steps used is reduced to a. minimum with consequent processing advantages and economy.

The outstanding results provided by the additives of the invention as lubricating oil additives will be apparent from the following specific examples illustrating the preparation of the additive and its use in the oil.

EXAMPLE I 170.7 pounds of finished brightstock having a viscosity of about 215 Saybolt Universal seconds at 210 F. were sulfonated with 68.4 pounds of percent oleum. The reaction mixture was agitated at all times and the temperature was maintained at 127-133 F. by controlling the rate of oleum addition and the temperature of the cooling water. The mixture was agitated for approximately three hours after all the acid was in. The temperature was held 125-130" F. The reaction mixture was'added to three volumes of aqueous isopropanol volume percent alcohol), agitated and allowed to settle at about 90 F.

After about one hour the phases had separated and the bottom phase was drawn off and discarded. This phase consisted of water, alcohol, and about 80 percent of the sulfuric acid present in the mixture.

The raffinate phase (sulfonic acids, unreacted oil, some sulfuric acid, alcohol and water) was mixed with about one volume of aqueous isopropanol (10.4 volume percent water), agitated, and allowed to settle 24 hours at 90 F. The bottom phase was drawn off. This phase contained some sulfuric acid, about 90 percent of the sulfonic acids, alcohol, water, and some oil. The rafiinate phase was again extracted with a one volume portion of aqueous alcohol 10.4 percent water by volume) and a phase separation was made. The rafiinate from this separation consisted of unreacted oil, some water and alcohol and a small amount of sulfonic acids. It was neutralized with lime, stripped of solvent, filtered and is used as high grade brightstock which has some detergent value due to the small amount of calcium sulfonate contained in it.

The last two extracts were combined, neutralized with lime, diluted with SAE-lO stock to facilitate handling, stripped of alcohol and water, diluted with one volume benzene to reduce viscosity, filtered, and the filtrate stripped of solvent. This solvent free material was the additive product and contained some diluent SAE-IO stock.

The yield of additive product on an SAE10 stock free'basiswas 57.6 weight percent based on theSAE'250 4 stock charged. The sulfated ash analysis of the SAE-10 stock free product was 7.68 weight percent.

A feature of this process was that no alcohol-water mixture having over 89.6 volume percent isopropanol was required. This is the alcohol-water azeotrope and there fore simplified solvent recovery.

EXAMPLE II Engine test data an additive product 1. CATERPILLAR L-l DIESEL Oil containing the calcium petroleum sulfonate of Example I in an amount of 88.4 millimols of calcium per gallon of finished oil (5.2 volume percent) was blended with SAE-30 oil and 0.60 percent Lubrizol 609 was used as an inhibitor. The test was made with Mil-O-2l04 fuel containing 0.4 percent sulfur with the following results:

120 hour rating Carbon Lacquer 99.6 Overall 98.1

All the above figures are based on 100.0 as perfect.

2. CATERPILLAR L1 DIESEL A 10W30 blend oil containing the calcium petroleum sulfonate of Example I in an amount of 265.2 millimols of calcium per gallon of oil (15.8 volume percent) was admixed with 3.9 volume percent Acryloid 618 and 0.72

volume percent Lubrizol 609. The oil was tested with Supplement I fuel (1 percent sulfur) giving the following results:

hour rating Carbon 90.0 Lacquer 99.4 Overall 96.4

All of the above figures are based on 100.0 as perfect.

3. CHEVROLET COLD ENGINE sLUDGE An SAE-30 oil blend containing the calcium petroleum sulfonate of Example I in an amount of 88.5 millimols of calcium per gallon of oil was utilized in the Chevrolet Cold Engine Sludge Test with 0.6 volume percent Lubrizol 609 as the inhibitor. The results were: oil ring plugging 9.3 (optimum 10.0); sludge rating 36.6 (optimum 50.0); piston varnish 7.4 (optimum 10.0); oil screen 9.8 (optimum 10.0); and overall rating 81.7 (optimum 100.0).

The foregoing results show that high quality oil additives are produced by the process of the invention even when the operating economies of the process are taken advantage of, the oils having excellent carbon, lacquer and sludge ratings.

EXAMPLE III A finished brightstock (1.277 pounds) having a viscosity of about 215 Saybolt Universal seconds at 210 F. was sulfonated with 0.266 pound of 20 percent oleum at 108 F. This mixture (1.308 pounds) was batch extracted with a one volume portion of solvent. (The solvent used throughout this example is 87 weight percent isopropyl alcohol and 13 weight percent water.) The raffinate phase was batch extracted with a one volume portion of the solvent. The rafiinate phase from this separation was also batch extracted with a one volume portion of solvent. The three extracts were combined and neutralized with lime. The third rafiinate was also neutralized with lime. The solvents, alcohol and water, were stripped from both portions. Both portions-extract 1 Zinc dialkyldithiophosphate.

A high molecular weight methacrylate polymer used as n V. I. improver.

{3 times oil ring plugging rating plus each ofthe other ratings given.

5 and raflinate-were dissolved in benzene and filtered to remove calcium sulfate and excess lime. The filtrates were stripped of benzene.

The final raffinate product (essentially unreacted oil) has the following analysis:

Yieldabout 64 Weight percent Weight percent sulfur=0.45 Weight percent sulfated ash=0.67 Sp. gr., 60/60 F.=O.904

SUS, 100 F.=4175 SUS, 210 F.=231

Viscosity index=105 This rafiinate product represented an improved brightstock because of its sulfonate content and the severe acid treating to which it has been subjected.

The final extract product (essentially calcium petroleum sulfonate) had the following analysis:

Yield=36 weight percent Sulfur=4.55 weight percent Sulfated ash=13.0 weight percent (this is about twice the normal ash) which comprises sulfonating a lubricating oil stock having a viscosity of 200 to 230 Saybolt Universal seconds at 210 F., treating the entire sulfonation product with an aqueous alcohol solution of substantially the azeotropic concentration, thereby separating the sulfonated material into an extract fraction and a rafiinate fraction, said alcohol having no more than 7 carbon atoms, neutralizing the extract with a basic metal compound, and recovering the resulting metal petroleum sulfonate.

2. The method of making a metal petroleum sulfonate which comprises sulfonating a lubricating oil stock having a viscosity of 200 to 230 Saybolt Universal seconds at 210 F., treating the entire sulfonated product with an aqueous alcohol solution, containing 5 to 40 percent alcohol to separate it into an extract and a rafi'inate, treating the rafiinate fraction with an aqueous alcohol solution of substantially the azeotropic concentration, thereby separating the sulfonated material into an extract fraction and a rafiinate fraction, said alcohol having no more than 7 carbon atoms, neutralizing the extract with a basic metal compound, and recovering the resulting metal petroleum sulfonate.

3. The method of making an alkaline earth metal petroleum sulfonate which comprises treating a lubricating oil stock having a viscosity of 200 to 230 Saybolt Universal seconds at 210 F. With oleum at an acid-to-oil weight ratio of 0.2 to 0.5, extracting the sulfonated mate rial With aqueous isopropyl alcohol of substantially the azeotropic concentration, neutralizing the resulting extract phase With an alkaline earth metal hydroxide, and recovering the resulting alkaline earth metal petroleum sulfonate.

4. The process of claim 3 in which the alkaline earth metal is calcium.

5. The method of making an alkaline earth metal petroleum sulfonate which comprises treating a lubricating oil stock having a viscosity of 200 to 230 Saybolt Universal seconds at 210 F. with oleum at an acid-to-oil Weight ratio of 0.2 to 0.5, treating the entire sulfonated product with an aqueous isopropyl alcohol containing 5 to 40 percent by weight alcohol to form a rafiinate phase and an extract phase, treating the raflinate phase with aqueous isopropyl alcohol of substantially the azeotropic concentration, neutralizing the resulting extract phase With an alkaline earth metal hydroxide, and recovering the result ing alkaline earth metal petroleum sulfonate.

References Cited in the file of this patent UNITED STATES PATENTS 1,935,666 Ramayya Nov. 21, 1933 2,414,773 Showalter Jan. 21, 1947 2,532,997 Cohen Dec. 5, 1950 

1. THE METHOD OF MAKING A METAL PETROLEUM SULFONATE WHICH COMPRISES SULFONATING A LUBRICATING OIL STOCK HAVING A VISCOSITY OF 200 TO 230 SAYBOLT UNIVERSAL SECONDS AT 210*F., TREATING THE ENTIRE SULFONATION PRODUCT WITH AN AQUEOUS ALCOHOL SOLUTION OF SUBSTANTIALLY THE AZEOTROPIC CONCENTRATION, THEREBY SEPARATING THE SULFONATED MATERIAL INTO AN EXTRACT FRACTION AND A RAFFINATE FRACTION, SAID ALCOHOL HAVING NO MORE THAN 7 CARBON ATOMS, NEUTRALIZING THE EXTRACT WITH A BASIC METAL COMPOUND, AND RECOVERING THE RESULTING METAL PETROLEUM SULFONATE. 